Re: Concurrency
"Distributed concurrency is fairly new and not solved as much as people expect it to be."
Depends on your definition of "new", folks were working on this problem before ARPAnet first started punting bytes around the place. Leslie Lamport et al wrote the "The Byzantine Generals Problem" paper ~1980, and it was not a new problem for them to solve even at that time...
From my point of view, academically, distributed computing/parallel processing is fairly mature, there are plenty of robust models and papers out there, the problem is that folks invest their time in looking for silver bullet frameworks rather than reading papers and applying grey matter.